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Pontiac Grand Prix: Real World MPG



  • blckthreeblckthree Posts: 153
    Your mileage is the same as mine. I don't run 90, but just over 80 and I will get 20-22mpg. City driving, without any highway driving, lots of traffic lights and stop and go traffic, I get more like 13-14.

    On a daily commute to work, I keep it around 70mph, and get about 24mpg. The mileage is acceptable to me, but I wish they wouldn't have put that sticker on that said you could get 28. I'll never see that.

    All this is with 87 octane fuel.

  • chats1chats1 Posts: 158
    I have a 2006 GXP. When I first got the car I was getting about 13-14 and a little upset because of what GM said we would get. Now, I have 10,000 miles on my car and the highest I have gotten is 26.5; the lowest 19 around town. I drive mostly on highways. I use only Amoco Ultimate as I did with my three previous GTP's. I am satisfied with my mileage. As far as the gas prices go, there is absolutely nothing you can do about it, so I don't even complain. I'm just worried about gas lines and not being able to get gas. I knew when I purchased this car that I would use more gas and my mileage would be less than on my GTP's but I didn't care. If I was to worry about gas, I would have bought a Toyota which didn't interest me at all. I am very pleased with this car and its performance. My brother was complaining about the gas, I told him to use a bike!! I think that the more mileage you put on the car, the better the gas mileage. That's how it has worked with my car.
  • Me too! I'm getting a whopping 14.3 MPG city, recently up from 12.1. My gxp has 2500 miles on it and fuel economy in town has been 12.1-12.4 up to the last tankful of 87. I guess it finally broke in. also it used a quart of oil by the time it had 1900 on it. My wife and I really adore the power and handling though, and I'm pleasantly surprised by the number of compliments we have recieved on it's styling and color(dark cherry).We're panning a trip to springfeild soon, can't wait to see some hiway numbers.
  • Took my 05 GXP on a road trip to vegas this weekend. 600 mile round trip. 11,500 miles on the car. Going i got 23.5 mpg. averaged about 70. coming home i got 23.9 mpg. averaged 70-80. Guess the mileage isnt going to improve. Miss my 2000 sls..same engine...would get 28! Those low profile tires suck. they ride hard and follow every crack in the road. Does anyone know if i can put a tire on the car with more rubber without the tire rubbing since the clearances are tight??
  • rmozolrmozol Posts: 124
    I thought that this engine was new in 2005? I know they made some iron-block 5.3 Vortec, but the all-aluminum was new I thought. 24 MPG isn't that bad either in that altitude. If you mean a wider tire, I doubt there's much more room. If you mean taller, with more sidewall to absorb the cracks, we might be out of luck too. You'd have to go to a thinner tire, with a higher aspect ratio; like a 235/60 x 18? Then the traction would stink since it would be narrower!
  • rayainswrayainsw Posts: 2,476
    "I thought that this engine was new in 2005?"

    The DoD version of the 5.3L V8 was new in 2005.
    I believe that " erichthecatt" is referring to the Bonneville GXP w/North*.
    - Ray
    Looking forward to driving 600+ miles this coming (long) weekend.
    At many (s)miles per gallon . .
  • Thanks Ray. I should have stated Bonneville. I was thinking of a taller tire. While i was sitting at a casino in vegas trying to win an 06 chrysler 300 for 15 cents, i noticed that the car had goodyear 225/60/18. It looked like quite a bit more rubber height. Does anyone know where i can go to compare the two tires? I dont want to mess up the speedo
  • rmozolrmozol Posts: 124
    I did some checking on Tire Rack's site, and found the difference. Some 225/60 x 18 are the same diameter as the stock fronts, and others are about 1.5" inches taller; it strictly depends upon brand. This would equate to about a 6% difference for a wide spread between the two. That would mean it would read 100 MPH, when it's really going 106 MPH. Not that bad at all.
  • bxdbxd Posts: 186
    If you want to soften up the ride, don't mess with the size of the tires. Pick a tire that is aimed at a quieter/softer ride instead of one that is fairly skewed towards performance. For example, for the front, Continental ContiProContact in original size are only $126 at the Tire Rack and rate very quiet, and nice riding, while not totally giving up handling. Or some Pirelli PZero Nero M&S but those are a lot more money.
  • gxpjoeypgxpjoeyp Posts: 38
    Im trying the freeway thing on my current tankful of gas,so far its around 22.3 on 80/20 freeway/city is anybody else watching there mpg and if so can you tell me what your getting? I know the epa says 28/17 which i understand is just an estimate with all the factors involved,but if i could avg 24 i will be satisfied.
    2006 gxp
    1513 miles and loving it!!!
  • chats1chats1 Posts: 158
    I have 11,500 on my 2006. I have gotten as high as 26.5. When I first got the car, I was getting 13-14. I was really surprised at that. But, I think, as you put more mileage on your car, you'll get better mileage. I did. I'm satisfied. I knew that when I bought the car the mileage probably wouldn't be as good as my 3 GTP's but I didn't care; I wanted this 8 cylinder and I also knew the gas prices would be high, but I didn't care about that either. Except for my hissing/humming I love the car. I can't help it if I'm a fanatic about my car. I said to the dealer I think I'm paranoid. They said, "you think?" They also told me to stay off of the Edmunds website. You can't believe everything you read!! Oh, well. Good luck with your car. What color is it? I like the fact that you don't see yourself coming and going. I've only seen one in a grocery store lot so far. When I first got the car and drove it down to South Jersey, my brother surprisingly said he liked it. That was quite a compliment coming from him. He used to race hsi 65 GTO. He had to check under the hood to see how they set everything up in this 8 cylinder. He was making me nervous and then all of a sudden he pulled a rag out. When preping it, the mechanic at the dealership left a red rag on the bar in front of the fan. My brother said it's a good thing it wasn't in the fan! It was red so he could see it easily. He was disgusted with that, though. Chats1
  • rayainswrayainsw Posts: 2,476
    Repost from last fall:

    GXP gas mileage November Thanksgiving 2005 trip

    The good news is that I (finally) exceeded 20 MPG for a full tank.

    The bad news is that I am afraid it is pretty clear that I will never achieve the highway EPA rating. (Unless the gas mileage improves as I add more miles – though at 7,000+ now, I doubt that.)

    I drove from Atlanta to Carrabelle, FL and back. I filled the tank once I cleared the metro area. I filled the tank again at 232 miles (last gas in Georgia) and filled again in Tifton, before re-joining I75 North for the slog home on Sunday PM. (I did not want to count that mileage, as the traffic became bad & worse – as feared \ expected.)

    I averaged these 2 fills, since they were not the pumps I typically use – and there are variances. The 2 fills = 470 miles. Total fuel used = 19.35 gal. Average MPG = 24.3. (Excel, not DIC.)

    I did not exceed 80 MPH on the Interstate section southbound. Once off the Interstate, the speed limits and (um) aggressive enforcement mean that I find 65 the highest ‘reasonable & prudent’ speed.

    A little experimenting with various steady speeds on relatively level roads strongly suggests that DoD is much more likely to engage at 60 – 70 than at any higher speeds. With resulting steep downslope to MPG as speeds rise above 70.

    = = =

    I have seen no significant difference in my MPG since then, and I am now nearly at 14,000 miles.

    I’d like better fuel mileage – but my ( um ) un-disciplined right foot and over 300 HP \ TQ suggests that I am not willing to sacrifice an occasional acceleration “burst” for another 1 or 2 overall MPG.

    Given how much fun I have when I can use my GXP’s performance, I am pretty happy with the fuel mileage.

    I will be taking exactly the same trip described above this weekend, leaving Saturday AM (early) and returning Tuesday. I will post an update.

    - Ray
    Looking forward to 6+ hours of “Quality Time” with my XM each way . .
  • blckthreeblckthree Posts: 153
    My GXP has 11,000 miles, I just took a 1500 mile trip with it. Speed was average of 80mph, mpg varied from 20.5 - 23, depending on when I had a head wind. If you can keep it below 70mph, you might do better, but I can't do that!

  • gxpjoeypgxpjoeyp Posts: 38
    Hey chats mine is black on black leather all the toys except the nav...Ive only seen 2 gxp's and they were both red i really like the dark cherry color too but that only came with the tan seats ugggghhh....
  • bubbaman999bubbaman999 Posts: 54
    Lets see, 2200 miles, so far. Mostly drive to work about 15 miles each way. About 10 freeway, 5 city and I have gotten from 20.5 to 23.7 for a high. The more I drive highway the better. Usually do cruise or I speed way too much. About 65 or so and the cruise does a better job of getting MPG and DoD shut off then my foot. Any significant increase in city driving side trips reduces the mileage to the low side 19-20. Running mid-grade gas, don't know if that makes a difference on mileage. AC always on, it is already 90-100 everyday. Plan a long trip later in the summer and will let you know. But for the simple fact I have a car with so much fun to drive the fact that I get 20s MPG is GREAT. I mean fullsize, comfortable, great handling, acceleration, all for something that gets in the 20s consistently. It is only costing me 3-4 gallons more a week (about $12) over my 03 Civic SI with significantly greater comfort, less road noise, better sounds, more power....Not too shabby.

    PS Sorry to offend the younger drivers, this old man (39), still would like to see the total buyer age stats.

  • chats1chats1 Posts: 158
    My Dark Cherry has the graphite leather interior. I wouldn't like the tan either. About the ac, I use mine all the time -- it works great, nice and cold -- no problems with it at all. That would have been my first complaint, before the hissing!!! Oh, I have everything too except for the nav. system. Chats1
  • rayainswrayainsw Posts: 2,476
    Left the Atlanta area at 6 AM Saturday. Stopped to fill the tank just South of the City.

    Kept the speed to 70 – 80 to my exit in Tifton, GA.

    My speeds off the Interstate were 45 – 65. Through a number of small towns, (and later) through the outskirts of Tallahassee, south to 98, then west.

    Filled at the (next to) last gas in Georgia. A/C was on about half the time:

    225 miles 24.5 MPG (DIC – Excel: 26.5).

    Destination was Carrabelle, FL – and my hosts used their (4 wheeled & water) vehicles, while mine sat idle . .

    On the return trip, I filled the tank again in Tifton.

    23.8 MPG – A/C on this whole leg. 248 miles. (Excel: 24.5)

    Traveling North on I75 on Tuesday AM, was able to maintain a steady 78 – 80 with cruise control on for just over 100 miles – to the rest area on the Macon Bypass. Settled in at 23.5 MPG for that segment, with the A/C on.

    I was alone in the car & only had weekend luggage.

    Just a few mileage data points . .

    Over 14,000 miles on the car & just over 400 hours on the motor.
    A relatively painless journey!
    - Ray
    Happy GXP driver . .
  • eagle75eagle75 Posts: 16
    My wife and I took a 700 mile trip from Wichita, KS to St. Paul, NE and back over the holiday weekend. Averaged 65-75 both ways with A/C on all the time. 27.1 mpg up, 25.5 back (DIC). Very happy with that. Best I ever got with the Bonneville GXP on same route was 23.5. 2,300 total miles on the car so far.
  • Bill,
    Did you use cruise? Mostly level terrain, I assume. Also what fuel type did you use? I think I may see a difference with premium versus mid-grade, but don't have enough samples to prove it.

  • eagle75eagle75 Posts: 16

    On cruise most of the way--pretty flat country around these parts--some rolling hills--this was an ocean bottom a bazillion years ago. I've been using regular unleaded from day one.

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